Sony ILCE-7S - Manual (Page 81)

3. Press the shutter button fully down to shoot the image.
Note
[Center Lock-on AF] may not function very well in the following situations:
The subject is moving too quickly.
The subject is too small, or too large.
The contrast between the subject and the background is poor.
It is dark.
The ambient light changes.
Lock-on AF does not work in the following situations:
In [Sweep Panorama] mode
When [Scene Selection] is set to [Hand-held Twilight] or [Anti Motion Blur]
When shooting in Manual Focus mode
When using the digital zoom
When the subject to be tracked disappears from the screen, Lock-on AF is released.
When [Center Lock-on AF] is set to [On], the camera may not be able to resume tracking
for a while after it loses the track of the subject.
[65] How to Use Using shooting functions Adjusting the focus
Focus-lock
Shoots images with the focus locked on the desired subject in auto focus mode.
1. MENU
→
(Camera Settings
) → [Focus Mode] → [Single-shot AF].
2. Place the subject within the AF area and press the shutter button halfway down.
The focus is locked.
3. Keep pressing the shutter button halfway down, and place the subject back in the
original position to re-compose the shot.